Aqueous ink for inkjet, inkjet recording method, inkjet recorded matter, and inkjet recording device

ABSTRACT

An aqueous ink for inkjet includes water, at least one hydrosoluble organic solvent each having a boiling point of 250° C. or lower; vinyl polymer particles containing a pigment, and polycarbonate-based urethane resin particles, wherein the aqueous ink for inkjet is used for an inkjet recording system including a heating step.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35U.S.C. §119(a) to Japanese Patent Application Nos. 2014-002501 and2014-104438, filed on Jan. 9, 2014 and May 20, 2014, respectively, inthe Japan Patent Office, the entire disclosures of which are herebyincorporated by reference herein.

BACKGROUND

Technical Field

The present invention relates to an aqueous ink for inkjet, an inkjetrecording method, inkjet recorded matter, and an inkjet recordingdevice.

Background Art

Inkjet technologies have been appealing in business field of, forexample, display, posters, and signboards.

In such industrial use, since porous recording media have problems withregard to light fastness, water resistance, and abrasion resistance,non-porous recording media such as plastic film are used. Accordingly,ink for such non-porous recording medium has been developed.

In this context, development of inkjet technology is in progress to useaqueous ink widely used at home so far, which is less burden onenvironment, for industrial use.

SUMMARY

The present invention provides an improved aqueous ink for inkjetincluding water, at least one hydrosoluble organic solvent each having aboiling point of 250° C. or lower; vinyl polymer particles containing apigment, and polycarbonate-based urethane resin particles, wherein theaqueous ink for inkjet is used for an inkjet recording system includinga heating step.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and attendant advantages of the presentinvention will be more fully appreciated as the same becomes betterunderstood from the detailed description when considered in connectionwith the accompanying drawings in which like reference charactersdesignate like corresponding parts throughout and wherein:

FIG. 1 is a schematic diagram illustrating the configuration of anembodiment of the inkjet recording device using the ink according to anembodiment of the present invention; and

FIG. 2 is a schematic diagram illustrating the configuration of anotherembodiment of the inkjet recording device using the ink according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

As a result of an investigation made by the present inventors, it wasfound that when an aqueous ink for inkjet containing water, one or moreparticular hydrosoluble organic solvent, vinyl polymer particlescontaining a pigment, and polycarbonate-based resin particles is used,drying property and high gloss, scratch resistance, ethanol resistance,and light fastness at image portions are improved even when images areprinted on a non-porous substrate Thus, the present invention was made.

That is, the present invention is an aqueous ink for inkjet containingwater; one or more hydrosoluble organic solvents each having a boilingpoint of 250° C. or lower; vinyl polymer particles containing a pigment,and polycarbonate-based urethane resin particles.

Also, the aqueous ink for inkjet is used in an inkjet recording systemincluding a heating process.

The aqueous ink for inkjet of the present disclosure is used for aninkjet recording system including a heating process and contains waterand contains one or more hydrosoluble organic solvents each having aboiling point of 250° C. or lower, vinyl polymer particles containing apigment, and polycarbonate-based urethane resin particles.

The aqueous ink for inkjet, the inkjet recording method, the inkjetrecorded matter, the inkjet recording device related to the presentdisclosure are described below.

It is to be noted that although the embodiments described below arepreferred embodiments described with various technically preferredlimitations, and the present invention is not limited thereto unlessotherwise described.

Since hydrosoluble organic solvents added to an aqueous ink generallyhas a higher boiling point than water and is not easily dried, anorganic solvent having a relatively low boiling point is added to obtaindrying properties. However, quick drying property is not obtained ingeneral without compromising the uniformity of a formed resin film,thereby degrading film fastness and gloss.

As a result of a continuous investigation about the relation between anexisting resin and a hydrosoluble organic solvent, the present inventorshave found that a uniform layer can be formed by using apolycarbonate-based urethane resin and a particular hydrosoluble organicsolvent.

In particular, such a polycarbonate-based urethane resin has excellentwater resistance, heat resistance, abrasion resistance, and weatheringproperties due to strong agglomeration force of a carbonate group and issuitable for printed matter used in a severe environment such asoutdoor. Accordingly, after a particular hydrosoluble organic solvent isapplied as ink together with polycarbonate-based urethane resin emulsionparticles, a uniform layer can be formed by moderate drying andacceleration of adhesion of resin emulsion particles, so that high levelof gloss is achieved at image portions. Furthermore, scratch resistanceand ethanol resistance are demonstrated. In addition, when nohydrosoluble organic solvent having a boiling point higher than 250° C.is contained, drying properties are ameliorated.

In addition, in the case of outdoor use (typically advertisement andsignboard), white ink is applied to the entire surface of a transparentplastic film, etc., to improve visibility. In such a case,conventionally, image fastness, for example, scratch resistance, is notsufficient after application of white ink. To the contrary, the ink ofthe present disclosure demonstrates strong image fastness even whenwhite ink is applied or used to form a layer.

In the present disclosure, ink containing the white pigment describedlater is referred to as white ink.

The other compositions of the ink of the present disclosure aredescribed next. The ink compositions of the present disclosure containsat least water, a hydrosoluble organic solvent, vinyl polymer particlescontaining a pigment, and polycarbonate-based urethane resin particles,and optionally contains a surfactant, an anti-septic and anti-fungusagent, a corrosion inhibitor, and a pH regulator.

Polycarbonate-based Urethane Resin Particles

Polycarbonate-based urethane resin particles for use in the presentdisclosure are described below. The polycarbonate-based urethane resinin the present disclosure is obtained by reaction conducted betweenpolycarbonate polyol and polyisocyanate.

It is possible to use as the polycarbonate polyol mentioned abovepolyols prepared by, for example, ester exchange reaction of acarboxylic acid ester and a polyol under the presence of a catalyst orreaction between phosgene and bisphenol A.

Specific examples of carboxylic acid esters include, but are not limitedto, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethylcarbonate, cyclocarbonate, and diphenyl carbonate.

Specific examples of the polyol mentioned above to react with thecarboxylic acid ester include, but are not limited, low-molecular weightdiol compounds such as ethylene glycol, diethylene glycol,1,2,-propylene glycol, dipropylene glycol, 1,4-butane diol, 1,5-pentanediol, 3-methyl-1,5-pentane diol, neopentyl glycol, and 1,4-cyclohexanediol; polyethylene glycol, and polypropylene glycol.

There is no specific limit to the polyisocyanate mentioned above.Specific examples thereof include, but are not limited to, aromaticpolyisocyante compounds such as 1,3-phenylene diisocyanate,1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI),2,6-tolylene diisocyanate, 4,4′-diphenylene methane diisocyanate (MDI),2,4-diphenyl methane diisocyanate, 4,4′-diisocynato biphenyl,3,3′-dimethyl-4,4′-diisocyanate biphenyl,3,3′-dimethyl-4,4′-diisocyanate, diphenyl methane, 1,5-naphtylenediisocyanate, m-isocyanate pheny sulphonyl isocyanate, p-isocyanatephenyl sulfonyl isocyanate, and p-isocyanate phenyl sulfonyl isocyante;aliphatic polyisocyanates compounds such as ethylene diisocyanate,tetramethylene diisocyanate, hexarnethylene diisocyanate (HDI),dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate,2,2,4-trimethyl hexarnethylene diisocyanate, lysine diisocyanate,2,6-diisocyante methylcaproate, bis(2-isocyanate ethyl)fumarate,bis(2-isocyanateethyl)carbonate, and 2-isocyanate ethyl-2,6-diisocyanatehexanoate; and alicyclic polycyanate compounds such as isophoronediisocyante (IPDI), 4,4′dicyclohexyl methane diisocyanate (hydrogenatedMDI), cyclohexylene diisocyante, methylcyclohexylene diisocyanate(hydrogenated TDI),bis(2-isocyanateethyl)-4-dichlorohexene-1,2-dicarboxylate,2,5-norbornane diisocyante, and 2,6-norbonane diisocyante. These can beused alone or in combination.

The ink of the present disclosure is expected to be use for the purposeof outdoor use, typically posters and signboards, so that an appliedlayer keeping an extremely high level of weathering property isdemanded. In terms of this, using aliphatic or alicyclic diisocyanatesis preferable. Furthermore, in the present disclosure, it is preferableto add at least one kind of alicyclic diisocyanate, thereby easilyacquiring a desired layer strength.

Of these, in particular, isophrone diisocyanate and dicyclohexyl methanediisocyanate are preferable. The ratio of alicyclic diisocyanate ispreferably 60% by weight or more in all the isocyanate compounds.

In the present disclosure, it is preferable to add polycarbonate-basedurethane resin particles in a resin emulsion form in whichpolycarbonate-based urethane resin particles are dispersed in an aqueousmedium. The ratio of the solids content in the resin emulsion ispreferably 20% by weight or more. The solids content being 20 by weightor more is preferable in terms of designing of prescription of ink Forexample, freedom of change and adjustment of the addition amount andratio of each ink composition material can be improved.

The urethane resin particles preferably has a volume average particlediameter of from 10 nm to 350 nm in light of liquid storage stabilityand discharging stability when ink is prepared.

In addition, when dispersing urethane resin particles in an aqueousmedium, it is possible to use a forcible emulsification type using adispersant. However, since such a dispersant tends to remain in a layer(film), thereby weakening the strength of the layer, a so-calledself-emulsification type, which has anionic property in its moleculestructure, is preferably used. As for the acid value, containing ananionic group within an acid value range of from 20 mgKOH to 100 mgKOH/gis preferable to impart excellent scratch resistance and chemicalresistance.

In addition, specific examples of the anionic group include, but are notlimited to, a carboxyl group, a carboxylate group, a sulufonic acidgroup, and a sulfonate group. Of these, it is preferable to entirely orpartially use a neutralized carboxylate group or sulfonate group tomaintain good water dispersion stability.

Specific examples of the basic compound usable to neutralize the anionicgroup include, but are not limited to, organic amines such as ammonium,triethyl amine, pyridine, and morpholine, alkanol amines such asmonoethanol amine, and metal salt compounds containing Na. K. Li, Ca,etc.

When using a forcible emulsification method, a nonion surfactant oranion surfactant can be used. Of the two, a nonion surfactant ispreferable in terms of water resistance.

Specific examples of the nonion surfactants include, but are not limitedto, polyoxyethylene alkyl ether, polyoxyethylene alkylene alkyl ether,polyoxyethylene derivatives, polyoxyethylene aliphatic acid esters,polyoxyethylene polyol aliphatic acid ester, polyoxyethylene propylenepolyol, sorbitan aliphatic acid ester, polyoxyethylene curable ricinus,polyoxyalkylene polycyclic phenyl ether, polyoxyethylene alkyl amine,alkyl alkanol amide, and polyalkylene glycol (meth)acrylate. Of these,polyoxyethylene alkyl ether, polyoxyethylene aliphatic acid esters,polyoxyethylene sorbitan aliphatic acid ester, and polyoxyethylene alkylamine are preferable.

Specific examples of the anionic surfactants include, but are notlimited to, alkyl sulfuric acid ester salts, polyoxyethylene alkyl ethersulfuric acid salts, alkyl benzene sulfonic acid salts, α-olefinesulfonic acid salts, methyl lauryl acid salts, sulfosuccinic acid salts,ether sulfonic acid salts, ether carboxylic acid salts, aliphatic acidsalts, naphthalene sulfonic acid formalin condensed compounds, alkylamine salts, quaternary ammonium salts, alkyl betaine, and alkyl amineoxide. Polyoxyethylene alkyl ether sulfuric acid salts and sulfosuccinicsalts are preferable.

The addition amount of a surfactant is from 0.1% by weight to 30% byweight and preferably from 5% by weight to 20% by weight to the amountof urethane resin. Within the range of from 0.1% by weight to 30% byweight, since the layer forming property of a urethane resin emulsion isnot inhibited, an ink having excellent attachability and waterresistance is obtained. Also, when printed matter is overlapped orrolled up, blocking, i.e., strike-through of ink, never or littleoccurs, which is preferable.

Moreover, the urethane resin emulsion for use in ink of the presentdisclosure can optionally contains a hydrosoluble organic solvent, anantiseptic agent, a leveling agent, an antioxidant, a light stabilizer,and an ultraviolet absorbent.

The method of manufacturing polycarbonate-based urethane resin particlesfor use in the present disclosure is described below. The method ofmanufacturing polycarbonate-based urethane resin particles can be any ofconventional methods including the following method.

First, under the presence of no solvent or an organic solvent, aurethane prepolymer having an isocyanate group at its end is prepared byreacting a polycarbonate polyol and a polyisocyanate with an equivalentratio in which an isocyanate group is excessive.

Next, optionally the anionic groups in the urethane prepolymer having anisocyanate group at its end is neutralized by a neutralizer. Thereafter,subsequent to reaction with a chain elongating agent, the organicsolvent in the system is removed to obtain polycarbonate-based urethaneresin particles.

Specific examples of usable organic solvents include, but are notlimited to, ketone such as aetone and methyl ethyl ketone; ethers suchas tetrahydrofuran and dioxane, acetic acid esters such as ethyl acetateand butylacetate, nitriles such as acetonitrile, and amides such asdimethyl formamide, N-methyl pyrrolidone, and 1-ethyl-2-pyrrolidone.These can be used alone or in combination.

Polyamines or other compounds having active hydrogen atom are used asthe chain elongating agent.

Specific examples of the polyamine include, but are not limited to,diamines such as ethylene diamine, 1,2-propane diamine,1,6-hexamethylene diamine, piperazine, 2,5-dimethyl piperazine,isophorone diamine, 4,4′-dicyclohexyl methane diamine, 1,4-cyclohexanediamine, polyamines such as diethylene triamine, dipropylene triamine,and triethylene tetramine, hydrazines such as hydrazine, N,N′-dimethylhydrazine, and 1,6-hexamethylene bis hydrazine; dihydrazides such assuccinic acid dihydrazide, adipic acid dihydrazide, glutaric aciddihydrazide, sebacic acid dihydrazide, and isophthalic acid dihydrazide.

Specific examples of the other active hydrogen containing compoundsinclude, but are not limited to,glycols such as ethylene glycol,diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butane diol, 1,4-butane diol, hexamethylene glycol,saccharose, methylene glycol, glycerin, and sorbitol; phenols such asbisphenol A, 4,4′-duhydroxydiphenyl, 4,4′-dihydroxydiphenyl ether,4,4′-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, andhydroquinoe, and water. These can be used alone or in combination to thedegree that the storage stability of a coating agent is not degraded.

It is suitable to heat the ink of the present disclosure to reduce theremaining amount of the ink of the present disclosure, improve theattachability of the ink. Also the polycarbonate-based urethane resinparticles has good heat resistance.

It is not always necessary that the lowest layer forming temperature ofthe polycarbonate-based urethane resin particles for use in the presentdisclosure is room temperature or lower. However, when being heated, itis preferable that the lowest layer forming temperature is not higherthan the heating temperature.

The lowest layer forming temperature is preferably from 0° C. to atemperature at least 5° C. lower than the heating temperature and morepreferably from 25° C. to a temperature at least 10° C. lower than theheating temperature.

In general, lower values of the lowest layer forming temperature meanbetter layer forming property. However, when the lowest layer formingtemperature is too low, the glass transition temperature of the resinalso becomes lower so that the strength of a formed layer isinsufficient.

The lowest layer forming temperature is the lowest of the temperaturesbelow which transparent continuous film is not foamed when apolycarbonate-based urethane resin emulsion is extended and thinly flownon a metal plate made of aluminum, etc. while raising the temperature.At temperatures lower than the lowest layer forming temperature, thepolycarbonate-based urethane resin emulsion is liquid or white powder.

The polycarbonate-based urethane resin for use in the present disclosurepreferably has a surface hardness of 100 N/mrn² or greater. In thisrange, the ink of the present disclosure forms a strong layer, whichleads to improvement of scratch resistance.

The surface hardness in the present disclosure is measured by thefollowing method: After applying a polycarbonate-based urethane resinemulsion to a glass slide to form a layer having a thickness of 10 μm,the resin emulsion is dried at 100° C. for 30 minutes to form a resinlayer. Using a micro surface hardness tester (FISCHERSCOPE HM2000,manufactured by Fischer Instruments K.K. Japan), the pressed-in depthwhen a Berkovich indenter is pressed in under a load of 9.8 mN isobtained, which is measured as Martens hardness described inISO14577-2002.

The addition amount of the polycarbonate-based urethane resin particlesin the ink of the present disclosure is preferably from 0.5% by weightto 10% by weight, more preferably from 1% by weight to 8% by weight, andfurthermore preferably from 3% by weight to 8% by weight in solidscontent conversion in the ink. When the addition amount is 0.5% byweight or more, since a sufficient layer is formed against a pigment,image fastness is improved. When the addition amount is 10% by weight orless, desired viscosity is obtained, which leads to stable ejection.Additionally, within the range, drying property is improved.

The ink of the present disclosure optionally contains a resin other thanpolycarbonate-based urethane resin particles. However, apolycarbonate-based urethane resin preferably accounts for 50% by weightor more and more preferably 70% by weight or more in the total amount ofthe resin added to the ink.

Specific examples of the optional resin particles include, but are notlimited to, acrylic resin particles, polyolefin resin particles, vinylacetate resin particles, vinyl chloride resin particles,fluorine-containing resin particles, polyether resin particles, andpolyester resin particles.

Pigment

Next, the pigment for use in the present disclosure is described. In thepresent disclosure, ink for recording containing each pigment of cyan,magenta, yellow, black, white, etc. can be used. In the presentdisclosure, the ink contains vinyl polymer particles containing apigment.

Incidentally, “containing a pigment” means either or both of a state inwhich a pigment is encapsulated in a polymer particulate and a state inwhich a pigment is adsorbed to the surface of polymer particulates. Inthis case, all of the pigment mixed in the ink is not necessarilyencapsulated in or adsorbed to the polymer particulates and some of thecolorant is possibly dispersed in the emulsion unless they have anadverse impact. The pigment can be any pigment insoluble or littlesoluble in water that can be adsorbed by the polymer and selectedwithout any limitation.

Incidentally, “insoluble or little soluble in water” means that thedissolved amount of a coloring material to 100 parts by weight of waterat 25° C. is 10 parts by weight or less, preferably 5 parts by weight orless, and more preferably 1 part by weight or less. Also, “dissolved”means that separation or sedimentation of a coloring material is notvisually confirmed at the surface or the bottom of the aqueous solution.

The polymer for use in polymer particles contained in the pigment ispreferably insoluble in water and a vinyl polymer insoluble in water ispreferable. Specific examples thereof include, but are not limited to,polymers formed of structure units derived from an acrylate having anaryl alkyl group or an aryl group. Other suitable structure units derivefrom monomers containing salt producing groups, styrene-based macromers,hydrophobic monomers, (meth)acrylonitrile, monomers having aromatic ringother than styrene, silicone-based macromers having a polymerizablegroup at one end, and alkylmethacrylate-based macromers. In addition, itis possible to contain a hydroxy group, and a structure unit derivedfrom a (meth)acrylate having an alkyl group having 1 to 22 carbon atomsand preferably 1 to 18 carbon atoms.

Specific examples of the styrene-based macromer include, but are notlimited to AS-6, AS-6S, AN-6, AN-6S, HS-6S, and HS-6 (all manufacturedby TOAGOSEI CO., LTD.)

It is preferable that the vinyl polymer mentioned above contains atleast one kind selected from the groups formed of structure unitsderived from at least one of an acrylate having an arylalkyl group, anacrylate having an aryl group, a styrene-based macromer, or an alkylmethacrylate-based macromer.

The volume average particle diameter of the polymer particulates(colored particles) containing the pigment mentioned above is preferablyfrom 0.01 μm to 0.16 μm in the ink Within the range of 0.01 μm to 0.16μm, an ink is obtained which has excellent ejection stability, imagequality, and image fastness.

As the color of the pigment, specific examples thereof include, but arenot limited to, black, colors, and white forming the background fortransparent film. These can be used alone or in combination. The ink ofthe present disclosure is suitably used as the white pigment.

Example of black are carbon blacks manufactured by a known manufacturingmethod such as channel method, an oil furnace method, a furnaces method,an acetylene black method, and a thermal black method.

Specific examples of the pigments for the colors include, but are notlimited to, C. I. Pigment Yellow 1 (fast yellow G), 3, 12 (disazo yellowAAA), 13, 14, 17, 23, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55,74, 81, 83 (disazo yellow HR), 95, 97, 98, 100, 101, 104, 108, 109, 110,117, 120, 128, 138, 150, 153, and 155.

Specific examples of the pigments for magenta color include, but are notlimited to, C. I. Pigment Red 1, 2, 3, 5, 17, 22 (brilliant fastscarlet), 23, 31, 38, 48:2 [permanent red 2B(Ba)], 48:2 [Permanent Red2B (Ca)], 48:3 [Permanent Red 2B(Sr)], 48:4 [Permanent Red 2B(Mn)],49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1,81 (Rhodamine 6G Lake), 83, 88, 92, 101 (rouge), 104, 105, 106, 108(cadmium red), 112, 114, 122 (dimethylquinacridone), 123, 146, 149, 166,168, 170, 172, 177, 178, 179, 185, 190, 193, 209, and 219.

Specific examples of the cyan pigments include, but are not limited to,C. I. Pigment Blue 1, 2, 15 (copper phthalocyanine blue R), 15:1, 15:2,15:3 (phthalocyanine blue G), 15:4, 15:6 (phthalocyanine blue E), 16,17:1, 22, 56, 60, and 63.

Specific examples of white include, but are not limited to, inorganicpigments such as titanium oxide, silicon oxide, zinc oxide, and bariumsulfide. Of these, titanium oxide is particularly preferable. Also,materials having a surface treated with hydroxide, oxide, or phosphateof metal elements such as Al, Si, and Zr are preferable.

Specific examples of intermediate color include, but are not limited to,C. I. Pigment Red 177, 194, and 224, C. I. Pigment Orange 43, C. I.Pigment Violet 3, 19, 23, and 37, and C. I. Pigment Green 7 and 36.

In addition, the addition amount of a pigment serving as coloringmaterial in an ink composition preferably ranges from about 0.1% byweight to about 10% by weight and more preferably from about 1% byweight to about 10% by weight Within this range, high image density isobtained, the image quality is improved, and good fixability andejection stability are obtained, so that clogging, etc. can besuppressed. In addition, if a pigment is contained in a polymerparticle, it is preferable that the mass (the total solids content) ofthe pigment and the polymer particle preferably satisfies the rangespecified above.

Hydrosoluble Organic Solvent

Next, the hydrosoluble organic solvent for use in the present disclosureis described.

Specific examples of the hydrosoluble organic solvents for use in thepresent disclosure include, but are not limited to, polyols such asethylene glycol, diethylene glycol, 1,2-propane diol, 1,3-propane diol,1,2-butane diol, 1,3-butane diol, 2,3-butane diol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol,dipropylene glycol, tripropylene glycol, polypropylene glycol,1,5-pentane diol, 1,6-hexane diol, glycerin, 1,2,6-hexane triol,2-ethyl-1,3-hexane diol, ethyl-1,2,4-butane triol, 1,2,3-butane triol,and petriol; polyol alkyl ethers such as ethylene glycol monoethylether, ethylene glycol monobutyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether, diethylene glycol monobutylether, tetraethylene glycol monomethyl ether, and propylene glycolmonoethyl ether; polyol aryl ethers such as ethylene glycol monophenylether and ethylene glycol monobenzyl ether; nitrogen-containingheterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone,N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone,ε-caprolactam, and γ-butyrolactone; amides such as formamide,N-methylformamide, and N,N-dimethylformamide; amines such asmonoethanolamine, diethanolamine, and triethanolamine; sulfur-containingcompounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol;propylene carbonate, and ethylene carbonate. These have to have boilingpoints of 250° C. or lower.

The one of more of the hydrosoluble organic solvents contained in theink of the present disclosure has a boiling point of 250° C. or lowerand preferably lower than 220° C.

Good drying property and high level of gloss are obtained by containingno hydrosoluble organic solvent having a boiling point higher than 250°C.

Of these, it is preferable to contain at least one compound selectedfrom the group consisting of 1,2-propane diol, 1,3-propane diol,1,2-butane diol, 1,3-butane diol, and 2,3-butane diol. Such hydrosolubleorganic solvents have good compatibility with polycarbonate-basedurethane resins, so that ink having more excellent layer formingproperty and a high level of gloss is easily obtained.

The total amount of the hydrosoluble organic solvent in ink ispreferably from 20% by weight to 70% by weight and more preferably from30% by weight to 60% by weight. When the total amount ranges from 20% byweight to 70% by weight, ink is not easily dried and can suitablymaintain viscosity. As a result, it is possible to obtain an ink havingexcellent ejection stability without excessive drying or viscosityincrease.

Water

Water for use in the present disclosure has no specific limit Specificexamples thereof include, but are not limited to, deionized water,ultrafiltered water, Mill Q water, distilled water, and ultra purewater. The amount of water in the ink for inkjet recording has nospecific limit and can be selected to a particular application.

Ultraviolet Absorber

Next, the ultraviolet absorber for use in the present disclosure isdescribed. Such an ultraviolet absorber is added to improve imagefatness and in particular light fastness. There is no specific limit tothe ultraviolet absorber and specific examples thereof include, but arenot limited to, benzophenone-based ultraviolet absorbers,benzotriazole-based ultraviolet absorbers, salicylate-based ultravioletabsorbers, cyanoacrylate-based ultraviolet absorbers, and nickel complexsalt-based ultraviolet absorbers, oxalic acid anilide-based ultravioletabsorbents, and triazine-based ultraviolet absorbers. Specific compoundsare as follows.

Specific examples of the benzophenone-based ultraviolet absorbersinclude, but are not limited to, 2-hydroxy-4-n-octoxybenzophenone,2-hydroxy-4-n-dodecyloxy benzophenone, 2,4-dihydroxy benzophenone,2-hydroxy-4-methoxybenzophenone, and 2,2′,4,4′-tetrahydroxybenzophenone.

Specific examples of the benzotriazole-based ultraviolet absorbersinclude, but are not limited to, 2-(2′-hydroxy-5′-tert-octylphenyl)benzotriazole, 2-(2′-hydroxy-5′-methylphenyl)benzo triazole,2-(2′-hydroxy-4′-octoxyphenyl)benzo triazole, and2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzo triazole.

Specific examples of the salicylate-based ultraviolet absorbers include,but are not limited to, phenyl salicylate, p-tert-butylphenylsalicylate, and p-octylphenyl salicylate.

Specific examples of the cyanoacrylate-based ultraviolet absorbersinclude, but are not limited to, ethyl-2-cyano-3,3′-diphenyl acrylate,methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate, andbutyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate.

Specific examples of the nickel complex salt-based ultraviolet absorbersinclude, but are not limited to, nickel-bis(octylphenyl)sulfide,2,2′-thiobis(4-tert-octyl ferrate)-n-butylamine nickel (II),2,2′-thiobis(4-tert-octyl ferrate)-2-ethylhexyl amine nickel (II), and2,2′-thiobis(4-tert-octyl ferrate)triethanol amine nickel (II).

The triadine-based ultraviolet absorbers are available on market.Specific examples thereof include, but are not limited to, TINUVIN400-DW, TINUVIN 477-DW, and TINUVIN 479-DW (all manufactured by BASF).

These can be used alone or in combination.

The content of the ultraviolet absorber is preferably from 0.5% byweight to 20% by weight and more preferably from 1% by weight to 15% byweight as the effective component in ink. When the content is 0.5% byweight or more, the functionality of the absorber is sufficientlydemonstrated. In addition, if the content is 20% by weight or less, nocrystal of an ink precipitates around nozzles when the ink is dried.

Surfactant

As for the ink of the present disclosure, a surfactant can be added soas to secure the wettability of the ink to a recording medium. Theaddition amount of a surfactant is preferably from 0.1% by weight to 5%by weight as the effective component in ink. When the addition amount is0.1% by weight or more, the wettability of an ink to a non-poroussubstrate is secured, thereby improving the image quality. When theaddition amount is 5% by weight or less, ink tends not to foam so thatexcellent ejection stability is achieved.

Within this range, the surfactant can be any surfactant with nolimitation.

The surfactant can be any of an amphoteric surfactant, a nonionicsurfactant, and an anionic surfactant. Considering the relation betweenthe dispersion stability of a coloring material and the image quality,nonionic surfactants are preferable, which include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine,polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer,sorbitan aliphatic acid esters, polyoxyethylene sorbitan aliphatic acidesters, and adducts of acetylene alcohol with ethylene oxides, etc. Inaddition, it is possible to add a fluorine-containing surfactant and/orsilicone-based surfactant depending on prescription.

Other Additives

Examples of other additives include, preservatives and fungicides,corrosion inhibitors, and pH regulators.

Specific examples of preservatives and fungicides include, but are notlimited to, 1,2-benzisothiazoline-3-on, sodium benzoate, dehydrosodiumacetate, sodium sorbate, pentachlorophenol sodium, and 2-pyridinethiol-l-oxide sodium.

Specific examples of the corrosion inhibitors, but are not limited to,acid sulfite, thiosodium sulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol quaternary nitride, and dicyclohexylammonium nitrite.

The pH regulator can be any material that can adjust pH to a desiredvalue without an adverse impact on an ink to be prescribed. Specificexamples thereof include, but are not limited to, hydroxides of alkalimetal elements such as lithium hydroxide, sodium hydroxide, andpotassium hydroxide; carbonates of alkali metals such as lithiumcarbonate, sodium carbonate, and potassium carbonate; hydroxides ofquaternary ammonium, amines such as diethanol amine and triethanolamine; ammonium hydroxide, and hydroxides of quaternary phosphonium.

The ink of the present disclosure is manufactured by dissolving the inkcomponents mentioned above in an aqueous medium followed by optionalmixing and stirring. Typically, a stirrer using a stirring wing, amagnetic stirrer, a high performance disperser etc., can be used formixing and stirring but the method of manufacturing ink does not affectthe present disclosure.

The ink of the present disclosure can produce images having excellentgloss and image fastness on a non-porous substrate. The non-poroussubstrate can be in particular plastic film such as polyvinyl chlorideresin film, polyethylene terephthalate (PET) film, and polycarbonatefilm Also, the ink of the present disclosure is suitable for othernon-porous substrates and conventionally used porous media such as plainpaper or inorganic coated porous media.

The ink of the present disclosure can be used to print high qualityimages on non-porous media. However, it is more preferable to heat arecording medium in terms of forming an image with higher quality,abrasion resistance, and attachability and demonstration of highperformance under high speed performance printing conditions.

The heating temperature can be changed depending on the kind and amountof a hydrosoluble organic solvent contained in ink and the lowest layerforming temperature of an added resin. It also can be changed dependingon the kind of a recording medium to be printed. The heating temperatureis preferably high in terms of drying property and layer formingtemperature. However, if the heating temperature is too high, arecording medium on which an image is printed is damaged or an ink headis also heated unnecessarily, thereby causing non-ejection of ink. Thisis not preferable. The heating temperature is preferably from 40° C. to120° C. and more preferably from 60° C. to 90° C.

Inkjet Recording Device

The inkjet recording device of the present disclosure includes at leasta printing device to print an image on a recording medium and a heatingdevice to heat the recorded matter. Moreover, the image recording deviceoptionally has an ink ejection device to eject an aqueous ink for inkjetto form an image by applying an energy thereto and a transfer device totransfer a non-porous substrate including plastic film such as vinylchloride resin film, PET film, and polycarbonate film, and otherrecording media.

The ink ejection device ejects the aqueous ink of the present disclosureto form an image by applying a stimulus to the ink. The ink ejectiondevice has no specific limit and can be selected to a particularapplication. For example, various recording heads (ink ejection head)are usable. In particular, an ink ejection device is preferable whichhas a head having multiple nozzle arrays and a sub-tank thataccommodates an ink supplied from a liquid storing tank and supplies theliquid to the head.

It is preferable that the sub-tank mentioned above has a negativepressure producing device to produce a negative pressure in thesub-tank, an air releasing device to release air in the sub-tank, and adetector to detect whether there is ink therein by the difference ofelectric resistances.

The stimulus mentioned above has no specific limit and can be selectedto a particular application. For example, heat (temperature), pressure,vibration, and light can be suitably used as the stimulus. These can beused alone or in combination. Among these, heat and pressure arepreferable.

Examples of the device to generate such a stimulus include a heater, apressurization device, a piezoelectric element, a vibrator, anultrasonic oscillator, light, etc. Specific examples thereof include,but are not limited to, a piezoelectric actuator as the piezoelectricelement, a thermal actuator that utilizes a phase change caused by filmboiling of liquid using an electric heat conversion element such as aheat element, a shape-memory alloy actuator that uses the metal phasechange due to temperature change, and an electrostatic actuator thatuses an electrostatic force.

How the ink is ejected has no specific limit and can be selecteddepending on the kind of stimuli mentioned above. For example, in a casein which “heat” is applied as a stimulus, a method can be used whichincludes applying thermal energy according to recording signals to inkin a recording head by, for example, a thermal head to generate foams inthe ink, thereby ejecting and spraying the ink as droplets from thenozzles of the recording head due to the pressure of the foam.

In addition, in a case in which the stimulus is “pressure”, for example,a method can be used in which ink is ejected and sprayed from the nozzleholes of a recording head as droplets by applying a voltage to apiezoelectric element attached to the position of a pressure roomlocated in the ink flow path in the recording head, thereby bending thepiezoelectric element, resulting in a decrease in the volume of thepressure room. By these, a mechanical energy can be applied to ink.

In the present disclosure, it is preferable to eject ink by applying avoltage to a piezoelectric element.

No heat is generated by the piezoelectric system, which is advantageousto eject ink containing a resin. This is particularly suitable to subdueclogging in nozzles when ink containing a small amount of wetting agentis used.

In addition, to prevent non-ejection of ink caused by clogging ofnozzles, it is preferable to conduct false scanning by applying to apiezoelectric element a voltage above which ink is ejected. Furthermore,before false scanning reaching an amount corresponding to one pageprinting, it is preferable to operate ejection of ink to an ink storingportion.

In addition, it is preferable to include a scraper to scrape ink fixatedon a receiver of false ejection. Using a wiper or a cutter is preferableas the scraper.

In addition, the inkjet recording device of the present disclosureoptionally includes a transfer device to transfer a recording medium. Asthe transfer device, known transfer devices such as a transfer rollerand a transfer belt are suitable.

In addition, the inkjet recording device of the present disclosureoptionally includes a heating device to fix ink droplets on a recordingmedium such as a non-porous substrate.

As the heating device (heater), one or more known heating devices can beselected.

As the heating device, for example, devices for a forced-air heating,radiation heating, conductive heating, high frequency drying, ormicrowave drying are usable. These can be used alone or in combination.

An embodiment of the inkjet recording device of the present disclosureis described in detail with reference to the drawings. In thedescription, non-porous substrates are used but the present disclosureis not limited thereto.

FIG. 1 is a schematic diagram illustrating the inkjet recording deviceaccording to an embodiment of the present disclosure.

The inkjet recording device 101 illustrated in FIG. 1 has a sheet feedertray 102 to feed recording media placed in the inkjet recording device101, an ejection tray 103 attached to the inkjet recording device 101,which stores the recording media (non-porous substrate) on which imagesare recorded (formed), and an ink cartridge installation unit 104. Onthe upper surface of the ink cartridge installation unit 104 is arrangedan operating portion 105 including operation keys, a display, etc. Theink cartridge installation unit 104 has a front cover 115 that isopenable and closable to detach and attach an ink cartridge 200. In FIG.1, the reference numerals 111 and 112 represent an upper cover and afront face, respectively.

Inside the inkjet recording device 101, as illustrated in FIG. 2, aguide rod 131 serving as a guiding member that laterally bridges sideplates provided on the right hand side and left hand side and a stay 132hold a carriage 133 slidably movable in the main scanning direction. Amain scanning motor moves the carriage 133 for scanning.

The carriage 133 has a recording head 134 having four inkjet recordingheads that eject ink droplets of each color of yellow (Y), cyan (C),magenta (M), and black (Bk) while multiple ink discharging mouths arearranged in the direction crossing the main scanning direction with theink droplet ejection direction downward.

In addition, it is an option to provide an inkjet head to eject whiteink droplets to the recording head 134. In such a case, the number ofthe heads for inkjet recording becomes five in the recording head 134.The number of the recording heads is four in FIGS. 1 and 2 but is notlimited thereto. Other optional recording heads are provided accordingto other color inks used in addition to the white ink.

As the heads for inkjet recording that form the recording head 134, itis possible to use a device having an energy-generating device to eject(discharge) ink such as a piezoelectric actuator such as a piezoelectricelement, a thermal actuator that utilizes the phase change caused byfilm boiling of liquid by using an electric heat conversion element suchas a heat element, a shape-memory alloy actuator that uses the metalphase change due to the temperature change, and an electrostaticactuator that uses an electrostatic force.

The carriage 133 has sub tanks 135 for each color to supply each colorink to the recording head 134. The ink of ink set is supplied andreplenished to the sub tank 135 from the ink cartridge 200 mounted ontothe ink cartridge installation unit 104 via a tube for supplying ink.

A sheet feeding unit to feed a non-porous substrate 142 loaded on anon-porous substrate loader (pressure plate) 141 of the sheet feedertray 102 includes a half-moon shape roller (sheet feeding roller 143) toseparate and feed the non-porous substrate 142 one by one from thenon-porous substrate loader 141 and a separation pad 144 that is made ofa material having a large friction index and biased towards the sheetfeeding roller 143.

A transfer unit to transfer the non-porous substrate 142 fed from thesheet feeding unit on the lower side of the recording head 134 has atransfer belt 151 to electrostatically adsorb and transfer thenon-porous substrate 142, a counter roller 152 to transfer thenon-porous substrate 142 fed from the sheet feeding unit via a guide 145while pinching the non-porous substrate 142 with the transfer belt 151,a transfer guide 153 to make the non-porous substrate 142 trace thetransfer belt 151 by changing the transfer direction of the non-poroussubstrate 142 being sent substantially vertically upward bysubstantially 90°, a front end pressure roller 155 biased towards thetransfer belt 151 by a pressure member 154, and a charging roller 156 tocharge the surface of the transfer belt 151.

The transfer belt 151 has an endless form, stretched between a transferroller 157 and a tension roller 158 and is rotatable in the belttransfer direction. This transfer belt 151 has, for example, a top layerserving as a non-porous substrate adsorption surface made of a resinmaterial such as a copolymer (ETFE) of tetrafluoroethylene and ethylenewith no resistance treatment having a thickness about 40 μm, and abottom layer (intermediate resistance layer, earth layer) made of thesame material as that for the top layer with resistance treatment withcarbon. On the rear side of the transfer belt 151, a guiding member 161is arranged corresponding to the printing area by the recording head134.

A discharging unit to discharge the non-porous substrate 142 on whichimages are recorded by the recording head 134 includes a separation claw171 to separate the non-porous substrate 142 from the transfer belt 151,a sheet-ejection roller 172, and a sheet discharging roller 173. Thenon-porous substrate 142 is dried by heat wind by a fun heater 174 andthereafter output to a sheet ejection tray 103 arranged below thesheet-ejection roller 172.

A duplex printing sheet feeding unit 181 is detachably attached to therear side of the inkjet recording device 101.

The duplex printing sheet feeding unit 181 takes in and reverses thenon-porous substrate 142 that is returned by the reverse rotation of thetransfer belt 151 and feeds it again between the counter roller 152 andthe transfer belt 151. A manual sheet feeding unit 182 is provided onthe upper surface of the duplex printing sheet feeding unit 181

In this inkjet recording device, the non-porous substrate 142 isseparated and fed from the sheet feeding unit one by one substantiallyvertically upward, guided by the guide 145, and transferred while beingpinched between the transfer belt 151 and the counter roller 152.Furthermore, the front end of the non-porous sheet 142 is guided by thetransfer guide 153 and pressed against the transfer belt 151 by thefront end pressure roller 155 to change the transfer directionsubstantially 90°.

Since the transfer belt 151 is charged by the charging roller 156 atthis point in time, the non-porous substrate 142 is electrostaticallyadsorbed to the transfer belt 151 and transferred. By driving therecording head 134 according to the image signal while moving thecarriage 133, ink droplets are discharged to the non-porous substrate142 not in motion to record an image for an amount corresponding to oneline and thereafter the non-porous substrate 142 is transferred in apredetermined amount to conduct recording for the next line.

On receiving a signal indicating that the recording has completed or therear end of the non-porous substrate 142 has reached the image recordingarea, the recording operation stops and the non-porous substrate 142 isejected to the sheet-ejection tray 103.

A serial type (shuttle type) in which the carriage scans is used in thisdescription but this is true in a line-type inkjet recording devicehaving a line type head.

The inkjet recording device of the present disclosure can be applied torecording systems employing inkjet recording system such as printers,facsimile machines, photocopiers, multi-functional machines(printer/facsimile/photocopier) for inkjet recording in particular.

Recorded Matter

On the recorded matter of the present disclosure, information or animage is recorded on a recording medium by using the ink of the presentdisclosure. The recording medium can be selected to a particularapplication and can be any of plain paper, gloss paper, special paper,cloth, film, transparent sheets, etc.

By the ink of the present disclosure, in particular when it is used fora non-porous substrate, images having good level of gloss and imagefastness can be produced. The non-porous substrate has no specific limitand can be any of recording media, for example, a recording mediumformed of a hydrophobic resin that never or little absorbs water such asvinyl chloride, polypropylene, polyethylene, and polycarbonate and arecording medium such as coated paper that absorbs water to some degreebut is slow at absorption, so that an aqueous ink is not easily dried inthe printing process of a typical inkjet recording at room temperatureand normal humidity, which causes trouble.

Such recorded matter can be used alone or in combination. The recordedmatter obtained in the present disclosure has a high degree of gloss andfriction (scratch) resistance and can be used for various applications.

Inkjet Recording Method

The inkjet recording method of the present disclosure includes steps ofprinting an image on a recording medium by thermal or mechanical energyaction on the aqueous ink for inkjet of the present disclosure obtainrecorded matter and heating the recorded matter. In addition, in theprinting step, it is preferable to use a non-porous substrate as therecording medium. When the ink of the present disclosure is used for anon-porous substrate, images having good level of gloss and imagefastness can be produced. The same thermal energy and mechanical energycan be used as those described above.

The printing device for use in the printing step has no particularlimitation and can be the ejection device described above. The heatingdevice for use in the heating step has no particular limitation and asdescribed above, can be devices for a forced-air heating, radiationheating, conductive heating, high frequency drying, or microwave drying.These can be used alone or in combination.

As described above, the heating temperature can be changed depending onthe kind and amount of a hydrosoluble organic solvent contained in inkand the lowest layer forming temperature of an added resin. It also canbe changed depending on the kind of a recording medium to be printed.The heating temperature is preferably high in terms of drying propertyand layer forming temperature. However, if the heating temperature istoo high, a recording medium on which an image is printed is damaged oran ink head is also heated, thereby causing non-ejection of ink This isnot preferable. The heating temperature is preferably from 40° C. to120° C. and more preferably from 60° C. to 90° C.

The inkjet recording method of the present disclosure optionallyincludes the steps of coating the entire surface of a recording mediumwith a white pigment serving as the aqueous ink for inkjet and coatingthe recording medium with pigments serving as aqueous ink for inkjetother than white pigments. Therefore, when an ink containing whitepigments is used, it is suitable to use the following recording method.The ink for inkjet recording containing white pigments is applied to theentire surface of a recording medium and thereafter the recorded matteris heated. According to this, for example, if a transparent film isused, the white ink is attached to the entire surface of the recordingmedium, the recorded matter is visible. The ink of the presentdisclosure has good drying property, high level of gloss, and strongabrasion resistance, so that it is possible to coat the entire surfaceof a non-porous substrate such as transparent film with the white ink.

Moreover, on a recording medium having the surface entirely coated withthe white ink, an ink having pigment other than the white pigment can beprinted and the recorded matter can be heated. According to this, theink for printing in the present disclosure can be printed on a recordingmedium which is coated with white ink to improve visibility. The heatingtemperature is within the same temperature as the heating temperaturedescribed above.

Having generally described preferred embodiments of this invention,further understanding can be obtained by reference to certain specificexamples which are provided herein for the purpose of illustration onlyand are not intended to be limiting. In the descriptions in thefollowing examples, the numbers represent weight ratios in parts, unlessotherwise specified.

EXAMPLES

The present disclosure is described in detail with reference to Examplesand Comparative Examples. However, the present disclosure is not limitedto these examples.

Preparation of Polycarbonate-based Urethane Resin Emulsion A

1,500 g of polycarbonate diol (reaction product of 1,6-hexane diol anddimethyl carbonate), 220 g of 2,2-dimethylol propionic acid (DMPA), and1,347 g of propylene glycol dimethyl ether (boiling point: 171° C.) werecharged in a reaction container equipped with a stirrer, a refluxcooling tube, and a thermometer in a nitrogen atmosphere followed byheating to 60° C. to dissolve DMPA.

Thereafter, 1,445 g of 4,4′-dicyclohexyl methane diisocyanate and 2.6 gof dibutyl tin dilaurylate (catalyst) were added followed by heating to90° C. to conduct urethanification reaction in five hours, therebyobtaining a urethane prepolymer having an isocyanate group at its end.

This reaction mixture was cooled down to 80° C. 149 g of triethylaminewas admixed therewith. 4,340 g was extracted from the admixed mixtureand added to a liquid mixture of 5,400 g of water and 15 g of triethylamine while being vigorously stirred.

Thereafter, 1,500 g of ice and 626 g of 35% by weight2-methyl-1,5-pentane diamine aqueous solution were added to conductchain elongation reaction followed by distillation away of the solventin such a manner that the solids content concentration was 30% to obtainpolycarbonate-based urethane resin emulsion A (urethane resin component:30%, water: 64%, dipropylene glycol dimethyl ether: 6%).

The thus-obtained polycarbonate-based urethane resin emulsion A wasapplied to a slide glass to form a layer having a thickness of 10 μm,the resin emulsion was dried at 100° C. for 30 minutes to form a resinfilm. Martens hardness of the film was measured by a micro surfacehardness tester (FISCHERSCOPE HM2000, manufactured by FischerInstruments K.K. Japan). It was 120 N/mm² when a Vickers indenter waspressed in under a load of 9.8 mN. The lowest layer forming temperatureof the thus-obtained polycarbonate-based urethane resin emulsion A was30° C.

Preparation of Polycarbonate-based Urethane Resin Emulsion B

Polycarbonate-based urethane resin emulsion B (urethane resin component:30%, water: 64%, dipropylene glycol dimethyl ether: 6%) was obtained inthe same manner as in the preparation of the emulsion A except that4,4′-dicyclohexyl methane diisocyanate was changed to hexamethylenediisocyanate. The film hardness of the polycarbonate-based urethaneresin emulsion B was measured similarly and the Martens hardness thereofwas 87 N/mm² The lowest layer forming temperature of the thus-obtainedpolycarbonate-based urethane resin emulsion B was 33° C.

Example 1

Preparation of Monoazo Yellow Pigment Containing Polymer ParticulateDispersion Element

After replacement with nitrogen gas in a flask equipped with amechanical stirrer, a thermometer, a nitrogen gas introducing tube, areflux tube, and a dripping funnel, 11.2 g of styrene, 2.8 g of acrylicacid, 12.0 g of lauryl methacrylate, 4.0 g of polyethlene glycolmethacrylate, 4.0 g of styrene macromer (AS-6, manufactured by TOA GOSEICO., LTD.), and 0.4 g of mercapto ethanol were charged in the flask andthe system was heated to 65° C.

A liquid mixture of 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 gof lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0g of hydroxyethyl methacrylate, 36.0 g of styrene macromer (AS-6,manufactured by TOA GOSEI CO., LTD.), 3.6 g of mercapto ethanol, 2.4 gof azobisdimethyl valeronitrile, and 18 g of methylethyl ketone weredripped into the flask in two and a half hours. After dripping, a liquidmixture of 0.8 g of azobis dimethyl valeronitrile and 18 g ofmethylethyl ketone was dripped to the flask in half an hour; Afterone-hour aging at 65° C., 0.8 g of azobisdimethyl valeronitrile wasadded followed by another one-hour aging; After the reaction wascomplete, 364 g of methylethyl ketone was added to the flask to obtain800 g of a polymer solution having a concentration of 50%.

After 28 g of the thus-obtained polymer solution, 26 g of yellow pigment(C. I. Pigment Yellow 74, manufactured by Dainichiseika Color ChemicalsMfg. Co. Ltd.), 13.6 g of 1 mol/L potassium hydroxide solution, 20 g ofmethylethyl ketone, and 30 g of deionized water were sufficientlystirred, the mixture was mixed and kneaded using a triple roll mill.

The thus-obtained paste was charged in 200 g of deionized water.Subsequent to sufficient stirring, methylethyl ketone and water weredistilled away using an evaporator to obtain a water dispersion elementof hydroinsoluble vinyl polymer particles having a solids content of 20%by weight. The average particle diameter (D50) of the thus-obtainedpolymer particles was 76 nm as measured by a particle size distributionmeasuring instrument (MICROTRAC UPA-EX150, manufactured by NIKKISO CO.,LTD.).

Using the liquid dispersion of polymer particles containing monoazoyellow pigment, the following recipe was mixed and stirred andthereafter filtrated by a polypropylene filter of 0.2 μm to prepare anink.

Liquid dispersion of polymer particles   15 parts containing monoazoyellow pigment: Polycarbonate-based urethane resin 7.5 parts (containing0.9 parts of emulsion A: dipropylene glycol dimethylether having aboiling point of 171° C.). Acrylic-based Resin Emulsion: 2 parts(VONCOAT R-3380-E, manufactured by DIC Corporation) SurfactantCH₃(CH₂)₁₂O(CH₂CH₂O)₃CH₂COOH:   2 parts Propylene glycol (boiling point:188° C.):   20 parts Diethylene glycol n butyl ether (boiling point:230° C.):   15 parts Preservatives and fungicides (PROXEL LV,  0.1 partsmanufactured by AVECIA GROUP): Deionized water 38.4 parts

Next, the thus-obtained ink was evaluated in the following manner.

The mixing ratio and the evaluation results of the ink of Example andComparative Example are shown in Tables 1 and 2. In Tables 1 and 2,blank means “no amount”.

Evaluation on Drying Property

After an inkjet printer (remodeled based on IPSiO GXe 5500 manufacturedby RICOH Co., Ltd.) having a heating fan was loaded with themanufactured ink and a solid image was printed on a white vinyl chloridesheet (IJ5331, manufactured by Sumitomo 3M Ltd.), the image was dried at60° C. by the heating fan to form an image. Thereafter, filter paper waspressed against the solid portion. The drying property of the ink wasevaluated based on the state of transfer of the ink to the filter paperaccording to the following criteria:

-   A: No transfer of ink to filter paper stops on drying condition of    60° C. for 15 minutes-   B: No transfer of ink to filter paper stops on drying condition of    60° C. for 30 minutes-   C: No transfer of ink to filter paper stops on drying condition of    60° C. for 60 minutes-   D: Transfer of ink to filter paper continues after drying at 60° C.    for 60 minutes

Evaluation of Image Gloss

After an inkjet printer (remodeled based on IPSiO GXe 5500 manufacturedby RICOH Co., Ltd.) having a heating fan was loaded with themanufactured ink and a solid image was printed on a white vinyl chloridesheet (IJ5331, manufactured by Sumitomo 3M Ltd.), the image was dried at60° C. by the heating fan to form an image. Thereafter, gloss at 60° ofthe solid image portion was measured by a gloss meter (4501,manufactured by BYK Gardener) and evaluated according to the followingcriteria.

-   A: Gloss at 60° 100% or greater-   B: Gloss at 60° from 81% to less than 100 %-   C: Gloss at 60° from 60% to 80%-   D: Gloss at 60° less than 60%

Evaluation on Scratch Resistance

After an inkjet printer (remodeled based on IPSiO GXe 5500 manufacturedby RICOH Co., Ltd.) having a heating fan was loaded with themanufactured ink and a solid image was printed on a white vinyl chloridesheet (IJ5331, manufactured by Sumitomo 3M Ltd.), the image was dried at60° C. by the heating fan to form an image. Thereafter, the solidportion was abraded by dried cotton (unbleached muslin No. 3) with aload of 400 g and evaluated about scratch (friction) resistanceaccording to the following criteria:

-   A: No change in image when abraded 50+ times-   B: Slight scratch observed when abraded 50 times but causing no    damage to image density in terms of practical use-   C: Image density degraded when abraded 21 times to 50 times-   D: Image density degraded when abraded 20− times

Evaluation on Ethanol Resistance

After an inkjet printer (remodeled based on IPSiO GXe 5500 manufacturedby RICOH Co., Ltd.) having a heating fan was loaded with themanufactured ink and a solid image was printed on a white vinyl chloridesheet (IJ5331, manufactured by Sumitomo 3M Ltd.), the image was dried at60° C. by the heating fan to form an image. The solid image portion wasabraded by a cotton applicator impregnated in 50% aqueous solution ofethanol. Ethanol resistance was evaluated by the degree of peeling ofthe film of the solid image portion according to the following criteria.

-   A: No peeling-off in solid image portion, no contamination on cotton    applicator-   B: No peeling-off in solid image portion but slight contamination on    cotton applicator-   C: Ink melted portion observed on solid image portion-   D: Ink on solid image portion peeled and at least one portion of PVC    film exposed

Evaluation on Light Fastness

After an inkjet printer (remodeled based on IPSiO GXe 5500 manufacturedby RICOH Co., Ltd.) having a heating fan was loaded with themanufactured ink and a solid image was printed on a white vinyl chloridesheet (IJ5331, manufactured by Sumitomo 3M Ltd.), the image was dried at60° C. by the heating fan to form an image. Each of the thus-obtainedimage samples was subject to an exposure test until the light exposurereached 2,600 kJ/m² by using a Xenon Weather-Ometer® (manufactured byAtlas Electrical Devices Co.,) on the condition that the outside filterand the inside filter used were TYPE S borosilicate glass while theblack panel temperature was set to 89° C. and 50% RH. Discolorationbefore and after the test was measured by X-Rite 938 (manufactured byX-Rite Co.) and the light fastness was obtained by the followingrelation to evaluate the light fastness (color difference ΔE×ab)according to the following criteria.

ΔE×ab=(ΔL×2+Δa×2+Δb×2)^(1/2)

A: ΔE×ab≦5

B: 5<ΔE×ab≦10

C: 10<ΔE×ab≦20

D: 20<ΔE×ab

Scratch Resistance

Thereafter, the solid image portion after the light fastness test wasabraded by dried cotton (unbleached muslin No. 3) with a load of 400 gto evaluate light fastness scratch (friction) resistance according tothe following criteria:

-   A: No change in image when abraded 50+ times-   B: Slight scratch observed when abraded 50 times but causing no    damage to image density in terms of practical use-   C: Image density degraded when abraded 21 times to 50 times-   D: Image density degraded when abraded 20− times

Example 2

The ink of Example 2 was manufactured in the same manner as in Example 1except that 20 parts of propylene glycol (boiling point: 188° C.) waschanged to 25 parts of 2,3-butane diol and 38.4 part of deionized waterwas changed to 33.4 parts. The thus-obtained ink was evaluated in thesame manner as in Example 1.

Example 3

The ink of Example 3 was manufactured in the same manner as in Example 2except that 15 parts of the liquid dispersion of monoazo yellow pigmentcontaining polymer was changed to 48 parts and 33.4 part of deionizedwater was changed to 0.4 parts. The thus-obtained ink was evaluated inthe same manner as in Example 1.

Example 4

The ink of Example 4 was manufactured in the same manner as in Example 2except that 7.5 parts of the polycarbonate-based urethane resin emulsionA was changed to 0.3 parts and 33.4 part of deionized water was changedto 40.6 parts. The thus-obtained ink was evaluated in the same manner asin Example 1.

Example 5

The ink of Example 5 was manufactured in the same manner as in Example 2except that 7.5 parts of the polycarbonate-based urethane resin emulsionA was changed to 12 parts and 33.4 part of deionized water was changedto 28.9 parts. The thus-obtained ink was evaluated in the same manner asin Example 1.

Example 6

The ink of Example 6 was manufactured in the same manner as in Example 2except that 7.5 parts of the polycarbonate-based urethane resin emulsionA was changed to 7.5 parts of the polycarbonate-based urethane resinemulsion B. The thus-obtained ink was evaluated in the same manner as inExample 1.

Example 7

The ink of Example 7 was manufactured in the same manner as in Example 2except that 7.5 parts of the polycarbonate-based urethane resin emulsionA was changed to 5 parts and 2 parts of the acrylic-based resin emulsionwas changed to 4.5 parts. The thus-obtained ink was evaluated in thesame manner as in Example 1.

Example 8

The ink of Example 8 was manufactured in the same manner as in Example 2except that 1 part of ultraviolet absorber (TINUVIN 479-DW, manufacturedby BASF) was added and 33.4 parts of the deionized water was changed to32.4 parts. The thus-obtained ink was evaluated in the same manner as inExample 1.

Example 9

The ink of Example 8 was manufactured in the same manner as in Example 2except that 1 part of ultraviolet absorber (TINUVIN 477-DW, manufacturedby BASF) was added and 33.4 parts of the deionized water was changed to32.4 parts. The thus-obtained ink was evaluated in the same manner as inExample 1.

Example 10

Preparation of Silicone Surface Reformed Titanium Dioxide

10 parts of titanium dioxide (CR-60, manufactured by ISHIHARA SANGYOKAISHA, LTD.) dried at 110° C. for two days by a reduced pressure drierwas charged into 200 mL flask equipped with a pressure equalizingdripping funnel followed by nitrogen replacement. A solution in which0.5 parts of reactive silicone oil (KF-99, manufactured by Shin-EtsuCo., Ltd.) was diluted with 40 parts of dehydrated toluene was graduallydripped from the dripping funnel to the flask followed by stirring.After the completion of dripping, the resultant was heated in an oilbath followed by distilling away toluene. Thereafter, reaction wasconducted at 150° C. for three hours. After completion of the reaction,solid portions were retrieved followed by washing with methanolsufficiently. The resultant was dried with a reduced pressure at 60° C.for one day to obtain silicone surface reformed titanium dioxide.

Preparation of Dispersion Element of Polymer Particle Containing WhitePigment

The dispersion element of polymer particles containing white pigment wasprepared in the same manner as in Example 1 except that the yellowpigment (C. I. Pigment Yellow 74, manufactured by Dainichiseika ColorChemicals Mfg. Co., Ltd.) was changed to 6 parts of the silicone surfacetreated titanium dioxide prepared as described above in the preparationof the dispersion element of polymer particles containing monoazo yellowpigment of Example 1.

The average particle diameter (D50) of the thus-obtained polymerparticles was 280 nm as measured by a particle size distributionmeasuring instrument (NANOTRAC UPA-EX150, manufactured by NIKKISO CO.,LTD.).

Next, a white ink was manufactured in the same manner as in Example 8except that 15 parts of the liquid dispersion of polymer particlescontaining monoazo yellow pigment was changed to 15 parts of the liquiddispersion of polymer particles containing white pigment.

The thus-obtained white ink was applied to the entire surface of atransparent polyethylene terephthalate (E5100, manufactured by TOYOBOCO., LTD.) instead of the white vinyl chloride sheet (IJ5331) followedby drying at 60° C. by the heating fan for the same evaluation as inExample 1. Only the white ink was applied to the entire surface of arecording medium in each evaluation as described above. The evaluationwas conducted with no solid image printed.

Example 11

The evaluation was made in the same manner as in Example 1 except that asolid image was printed with the ink manufactured in Example 2 after thewhite ink prepared in Example 10 was applied to the entire surface of arecording medium (transparent polyethylene terephthalate E5100,manufactured by TOYOBO CO., LTD.).

Example 12

The ink of Example 12 was manufactured in the same manner as in Example8 except that 25 parts of 2,3-butane diol (boiling point: 183° C.) waschanged to 25 parts of 1,2-butanediol (boiling point: 194° C.). Theobtained ink was evaluated in the same manner as in Example 1.

Example 13

The ink of Example 13 was manufactured in the same manner as in Example8 except that 25 parts of 2,3-butane diol (boiling point: 183° C.) waschanged to 25 parts of 1,3-popanediol (boiling point: 214° C.). Thethus-obtained ink was evaluated in the same manner as in Example 1.

Example 14

The ink of Example 14 was manufactured in the same manner as in Example8 except that 25 parts of 2,3-butane diol (boiling point: 183° C.) waschanged to 25 parts of 1,2-propanediol (boiling point: 187° C.). Thethus-obtained ink was evaluated in the same manner as in Example 1.

Example 15

The ink of Example 15 was manufactured in the same manner as in Example8 except that 25 parts of 2,3-butane diol (boiling point: 183° C.) waschanged to 25 parts of 1,3-butanediol (boiling point: 203° C.). Thethus-obtained ink was evaluated in the same manner as in Example 1.

Comparative Example 1

Preparation of Liquid Dispersion of Yellow Pigment Surfactant

30 parts of monoazo yellow pigment (C. I. Pigment Yellow 74,manufactured by Dainichiseika Color and Chemicals Mfg. Co., Ltd.), 10.0parts of polyoxyethylene styrene phenylether (nonionic surfactant,NOIGEN EA177, HLB value: 15.7, manufactured by DAI-ICHI KOGYO SEIYAKUCO.,LTD.), and 60.0 parts of deionized water were prepared.

The surfactant mentioned above was dissolved in the deionized waterfollowed by mixing with the pigment mentioned above. Subsequent tosufficient moistening, the resultant was dispersed by a wet typedispersing device (DYNO-MILL KDL A type, manufactured by Willy A.Bachofen AG) which was filled with zirconia beads having a diameter of0.5 mm at 2,000 rpm for two hours to obtain a primary pigment dispersionelement.

Thereafter, 4.26 parts of hydrosoluble polyurethane resin (TakelacW-5661, manufactured by Mitsui Chemicals, Inc., effective component:35.2% by weight, acid value: 40 mgKOH/g, molecular weight: 18,000) wasadded followed by sufficient stirring to obtain a liquid dispersion ofyellow pigment surfactant. The average particle diameter (D50) of thepigment dispersion element in the thus-obtained liquid dispersion ofyellow pigment was 62 nm.

Using the liquid dispersion of pigment, the following recipe was mixedand stirred and thereafter filtrated by a polypropylene filter of 0.2 μmto manufacture an ink

The ink of Comparative Example 1 was manufactured in the same manner asin Example 1 except that the dispersion element of polymer particlescontaining monoazo yellow pigment was changed to the pigment dispersionelement mentioned above: The thus-obtained ink was evaluated in the samemanner as in Example 1.

Comparative Example 2

The ink of Comparative Example 2 was manufactured in the same manner asin Example 1 except that no polycarbonate-based urethane resin emulsionA was added and 38.4 parts of deionized water was changed to 45.9 parts.The obtained ink was evaluated in the same manner as in Example 1.

Comparative Example 3

Using the ink of Example 1, a solid image was printed and not dried 60°C. by the heating fan after a solid image was printed. The image wasdried one night by leaving as was at 25° C. and thereafter evaluated inthe same manner as in Example 1.

Comparative Example 4

The ink of Comparative Example 4 was manufactured in the same manner asin Example 8 except that 25 parts of 2,3-butane diol (boiling point:183° C.) was changed to 25 parts of glycerin (boiling point: 290° C.).The thus-obtained ink was evaluated in the same manner as in Example 1.

Comparative Example 5

Preparation of Liquid Dispersion of White Pigment

11.4 parts of deionized water, 12 parts of 3-methyl-1,3-butane diol, 0.6parts of DISPERBYK-190 (manufactured by Byk Chemie Japan Co., Ltd.)serving as dispersant were placed in a vial container followed by lightstirring for unification. Thereafter, 6 parts of the silicone surfacereformed titanium dioxide prepared as described above was added theretofollowed by irradiation (600 W) with ultrasonic wave at 50° C. for threehours to obtain a liquid dispersion. This liquid dispersion wasgradually cooled down to room temperature to prepare a liquid dispersionof white pigment. The volume average particle diameter (D50) of thethus-obtained liquid dispersion of white pigment measured by a particlesize distribution measuring instrument (NANOTRAC UPA-EX150, manufacturedby NIKKISO CO., LTD.) was 231 nm

Next, an ink was manufactured in the same manner as in Example 8 exceptthat 15 parts of the liquid dispersion of polymer particles containingmonoazo yellow pigment was changed to 15 parts of the liquid dispersionof white pigment prepared as described above.

The thus-obtained white ink was applied to the entire surface of atransparent polyethylene terephthalate (E5100, manufactured by TOYOBOCO., LTD.) instead of the white vinyl chloride sheet (IJ5331) followedby drying at 60° C. by the heating fan for the same evaluation as inExample 1. Only the white ink was applied to the entire surface of arecording medium in each evaluation as described above. The evaluationwas conducted with no solid image printed.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Water Deionized water38.4 33.4 0.4 40.6 Hydrosoluble propylene glycol (bp 188° C.) 20 organicsolvent 2,3-butane diol (bp183° C.) 25 25 25 1,2-butane diol (bp 194°C.) 1,3-propane diol (bp 214° C.) 1,2-propane diol (bp 187° C.)1,3-butane diol (bp 203° C.) Diethylene glycol n-butyl ether 15 15 15 15(bp 230° C.) Glycerin (bp 290° C.) Water Polycarbonate-based urethaneresin 7.5 7.5 7.5 0.3 dispersible Emulsion A resin Acrylic-based resinemulsion 2 2 2 2 (R-3380-E) Polycarbonate-based urethane resin EmulsionB Ultraviolet TINUVIN 479-DW absorber TINUVIN 477-DW Liquid Liquiddispersion of yellow pigment dispersion of surfactant pigment Liquiddispersion of yellow pigment 15 15 48 15 containing polymer particleLiquid dispersion of white pigment containing polymer particle Liquiddispersion of white pigment surfactant SurfactantCH₃(CH₂)₁₂O(CH₂CH₂O)₃CH₂COOH 2 2 2 2 Preservatives Proxel LV 0.1 0.1 0.10.1 and fungicide Total of ink 100 100 100 100 Recording White WhiteWhite White medium vinyl vinyl vinyl vinyl chloride chloride chloridechloride Ink attachment Image Image Image Image area portion portionportion portion Drying A A A A property Gloss B A A B Scratch A A B Bresistance Ethanol A A B A resistance Light fastness B B A B Lightfastness B B B B (after test) friction resistance Example 5 Example 6Example 7 Example 8 Water Deionized water 28.9 33.4 33.4 32.4Hydrosoluble propylene glycol (bp 188° C.) organic solvent 2,3-butanediol (bp 183° C.) 25 25 25 25 1,2-butane diol (bp 194° C.) 1,3-propanediol (bp 214° C.) 1,2-propane diol (bp 187° C.) 1,3-butane diol (bp 203°C.) Diethylene glycol n-butyl ether 15 15 15 15 (bp 230° C.) Glycerin(bp 290° C.) Water Polycarbonate-based urethane resin 12 5 7.5dispersible Emulsion A resin Acrylic-based resin emulsion 2 2 4.5 2(R-3380-E) Polycarbonate-based urethane resin 7.5 Emulsion B UltravioletTINUVIN 479-DW 1 absorber TINUVIN 477-DW Liquid Liquid dispersion ofyellow pigment dispersion of surfactant pigment Liquid dispersion ofyellow pigment 15 15 15 15 containing polymer particle Liquid dispersionof white pigment containing polymer particle Liquid dispersion of whitepigment surfactant Surfactant CH₃(CH₂)₁₂O(CH₂CH₂O)₃CH₂COOH 2 2 2 2Preservatives Proxel LV 0.1 0.1 0.1 0.1 and fungicide Total of ink 100100 100 100 Recording White White White White medium vinyl vinyl vinylvinyl chloride chloride chloride chloride Ink attachment Image ImageImage Image area portion portion portion portion Drying B A A A propertyGloss A A A A Scratch A A B A resistance Ethanol A A B A resistanceLight fastness B B B A Light fastness B B B A (after test) frictionresistance Example Example Example Example 9 10 11 12 Water Deionizedwater 32.4 32.4 33.4 32.4 Hydrosoluble propylene glycol (bp 188° C.)organic solvent 2,3-butane diol (bp 183° C.) 25 25 25 1,2-butane diol(bp 194° C.) 25 1,3-propane diol (bp 214° C.) 1,2-propane diol (bp 187°C.) 1,3-butane diol (bp 203° C.) Diethylene glycol n-butyl ether 15 1515 15 (bp 230° C.) Glycerin (bp 290° C.) Water Polycarbonate-basedurethane resin 7.5 7.5 7.5 7.5 dispersible Emulsion A resinAcrylic-based resin emulsion 2 2 2 2 (R-3380-E) Polycarbonate-basedurethane resin Emulsion B Ultraviolet TINUVIN 479-DW 1 1 absorberTINUVIN 477-DW 1 Liquid Liquid dispersion of yellow pigment dispersionof surfactant pigment Liquid dispersion of yellow pigment 15 15 15containing polymer particle Liquid dispersion of white pigment 15containing polymer particle Liquid dispersion of white pigmentsurfactant Surfactant CH₃(CH₂)₁₂O(CH₂CH₂O)₃CH₂COOH 2 2 2 2 PreservativesProxel LV 0.1 0.1 0.1 0.1 and fungicide Total of ink 100 100 100 100Recording White Transparent Transparent White vinyl medium vinyl PET PET(After chloride chloride (E5100: white ink TOYOBO) applied entirely Inkattachment Image Entire Image Image area portion surface portion portionDrying A A A A property Gloss A A A A Scratch A A A A resistance EthanolA A A A resistance Light fastness A A A A Light fastness A A A A (aftertest) friction resistance

TABLE 2 Example Example Example Comparative 13 14 15 Example 1 WaterDeionized water 32.4 32.4 32.4 38.4 Hydrosoluble propylene glycol (bp188° C.) 20 organic solvent 2,3-butane diol (bp 183° C.) 1,2-butane diol(bp 194° C.) 1,3-propane diol (bp 214° C.) 25 1,2-propane diol (bp 187°C.) 25 1,3-butane diol (bp 203° C.) 25 Diethylene glycol n-butyl ether15 15 15 15 (bp 230° C.) Glycerin (bp 290° C.) Water Polycarbonate-basedurethane resin 7.5 7.5 7.5 7.5 dispersible Emulsion A resinAcrylic-based resin emulsion 2 2 2 2 (R-3380-E) Polycarbonate-basedurethane resin Emulsion B Ultraviolet TINUVIN 479-DW 1 1 1 absorberTINUVIN 477-DW Liquid Liquid dispersion of yellow pigment 15 dispersionof surfactant pigment Liquid dispersion of yellow pigment 15 15 15containing polymer particle Liquid dispersion of white pigmentcontaining polymer particle Liquid dispersion of white pigmentsurfactant Surfactant CH₃(CH₂)₁₂O(CH₂CH₂O)₃CH₂COOH 2 2 2 2 PreservativesProxel LV 0.1 0.1 0.1 0.1 and fungicide Total of ink 100 100 100 100Recording White vinyl White vinyl White vinyl White vinyl mediumchloride chloride chloride chloride Ink attachment Image Image ImageImage area portion portion portion portion Drying A A A B property GlossA A A C Scratch A A A B resistance Ethanol A A A B resistance Lightfastness A A A D Light fastness A A A D (after test) friction resistanceComparative Comparative Comparative Comparative Example 2 Example 3Example 4 Example 5 Water Deionized water 45.9 38.4 32.4 32.4Hydrosoluble propylene glycol (bp 188° C.) 20 20 organic solvent2,3-butane diol (bp 183° C.) 25 1,2-butane diol (bp 194° C.) 1,3-propanediol (bp 214° C.) 1,2-propane diol (bp 187° C.) 1,3-butane diol (bp 203°C.) Diethylene glycol n-butyl ether 15 15 15 15 (bp 230° C.) Glycerin(bp 290° C.) 25 Water Polycarbonate-based urethane resin 7.5 7.5 7.5dispersible Emulsion A resin Acrylic-based resin emulsion 2 2 2 2(R-3380-E) Polycarbonate-based urethane resin Emulsion B UltravioletTINUVIN 479-DW 1 1 absorber TINUVIN 477-DW Liquid Liquid dispersion ofyellow pigment dispersion of surfactant pigment Liquid dispersion ofyellow pigment 15 15 15 containing polymer particle Liquid dispersion ofwhite pigment containing polymer particle Liquid dispersion of whitepigment 15 surfactant Surfactant CH₃(CH₂)₁₂O(CH₂CH₂O)₃CH₂COOH 2 2 2 2Preservatives Proxel LV 0.1 0.1 0.1 0.1 and fungicide Total of ink 100100 100 100 Recording White vinyl White vinyl White vinyl Transparentmedium chloride chloride chloride PET (E5100: TOYOBO) Ink attachmentImage Image Image Entire area portion portion portion Drying B D D Aproperty Gloss D C C B Scratch D D D C resistance Ethanol D D D Cresistance Light fastness B B B B Light fastness D D D D (after test)friction resistance

According to the present invention, an ink is provided which has gooddrying property and image portions of the ink have high level of gloss,scratch resistance, and ethanol resistance even when the image isprinted on a non-porous substrate.

Having now fully described embodiments of the present invention, it willbe apparent to one of ordinary skill in the art that many changes andmodifications can be made thereto without departing from the spirit andscope of embodiments of the invention as set forth herein.

1. An aqueous ink for inkjet comprising: water; at least onehydrosoluble organic solvent each having a boiling point of 250° C. orlower; vinyl polymer particles comprising a pigment; andpolycarbonate-based urethane resin particles, wherein the aqueous inkfor inkjet is used for an inkjet recording system including a heatingstep to heat recorded matter formed by the aqueous ink, at a heatingtemperature in a range from 40° C. to 120° C.
 2. The aqueous ink forinkjet according to claim 1, wherein the pigment is a white pigment. 3.The aqueous ink for inkjet according to claim 1, further comprising anultraviolet absorbent.
 4. The aqueous ink for inkjet according to claim1, wherein the hydrosoluble organic solvent comprises at least onecompound selected from the group consisting of 1,2-propane diol,1,3-propane diol, 1,2-butane diol, 1,3-butane diol, and 2,3-butane diol.5. The aqueous ink for inkjet according to claim 1, wherein the vinylpolymer particles are synthesized from at least one of an acrylatehaving an arylalkyl group, an acrylate having an aryl group, astyrene-based macromer, or an alkyl methacrylate-based macromer. 6-8.(canceled).
 9. Printed matter obtained by using the ink of claim 1,comprising: a substrate; and a printed layer including the at least onehydrosoluble organic solvent each having a boiling point of 250° C. orlower, the vinyl polymer particles including a pigment; and thepolycarbonate-based urethane resin particles.
 10. An inkjet recordingdevice comprising: a printing device to print an image on a recordingmedium by using the aqueous ink for inkjet of claim 1 to obtain recordedmatter; and a heating device to heat the recorded matter at a heatingtemperature in a range from 40° C. to 120° C.
 11. The inkjet recordingdevice according to claim 10, wherein the ink used by the inkjetrecording device to obtain the recorded matter further comprises anultraviolet absorbent.
 12. The inkjet recording device according toclaim 10, wherein the hydrosoluble organic solvent in the ink used bythe inkjet recording device to obtain the recorded matter comprises atleast one compound selected from the group consisting of 1,2-propanediol, 1,3-propane diol, 1,2-butane diol, 1,3-butane diol, and 2,3-butanediol.
 13. The inkjet recording device according to claim 10, wherein thevinyl polymer particles in the ink used by the inkjet recording deviceto obtain the recorded matter are synthesized from at least one of anacrylate having an arylalkyl group, an acrylate having an aryl group, astyrene-based macromer, or an alkyl methacrylate-based macromer.
 14. Theinkjet recording device according to claim 10, wherein a minimalfilm-forming temperature of the polycarbonate-based urethane resinparticles in the ink used by the inkjet recording device to obtain therecorded matter is 25 degrees C. or higher.
 15. The inkjet recordingdevice according to claim 10, wherein a content rate of thepolycarbonate-based urethane resin particles in the ink used by theinkjet recording device to obtain the recorded matter is 0.5-10 percentby mass.
 16. The inkjet recording device according to claim 10, whereinthe ink used by the inkjet recording device to obtain the recordedmatter comprises no hydrosoluble organic solvents having a boiling pointhigher than 250 degrees C.
 17. The inkjet recording device according toclaim 10, wherein the ink used by the inkjet recording device to obtainthe recorded matter further comprises one of acrylic resin particles,polyolefin resin particles, vinyl acetate resin particles, vinylchloride resin particles, fluorine-containing resin particles, polyetherresin particles, and polyester resin particles.
 18. The inkjet recordingdevice according to claim 10, wherein the polycarbonate-based urethaneresin particles in the ink used by the inkjet recording device to obtainthe recorded matter has an average particle diameter of 10-350 nm. 19.The ink according to claim 1, wherein a minimal film-forming temperatureof the polycarbonate-based urethane resin particles is 25 degrees C. orhigher.
 20. The ink according to claim 1, wherein a content rate of thepolycarbonate-based urethane resin particles in the ink is 0.5-10percent by mass.
 21. The ink according to claim 1, comprising nohydrosoluble organic solvents having a boiling point higher than 250degrees C.
 22. The ink according to claim 1, further comprising one ofacrylic resin particles, polyolefin resin particles, vinyl acetate resinparticles, vinyl chloride resin particles, fluorine-containing resinparticles, polyether resin particles, and polyester resin particles. 23.The ink according to claim 1, wherein the polycarbonate-based urethaneresin particles has an average particle diameter of 10-350 nm.